The City of London is a small area in central London that historically constituted most of London but now only represents a tiny part of the larger metropolis. It remains an important financial center, on par with New York City, and was the world's primary business center throughout the 19th century. Today, it is known simply as "the City" and refers to both the physical area as well as the financial community located there within only one square mile.

1. London city

2. • The City of London is an area in central
London, England. In the mediaeval period it
constituted most of London, but the conurbation
has grown far beyond it.2 As the City’s
boundaries have remained almost unchanged
since the Middle Ages, it is now only a tiny part
of the metropolis, though it remains a notable
part of central London and holds city status in its
own right.

3. • The City is today a major business and financial centre,
ranking alongside New York City as the leading centre of
global finance;5 throughout the 19th century, the City served as the
world's primary business centre, and continues to be a major
meeting point for businesses to this day.6 London came top in the
Worldwide Centres of Commerce Index, published in 2008. The
other major financial district in London is Canary Wharf, 2.5 miles
(4.0 km) to the east.

4. The name "London" is now used for a wider area than just the City of London, which is
often known simply as "the City". This usage is documented as far back as the 16th
century. "The City" also denotes the trading and financial community based there. In this
context it is also colloquially known as the "Square Mile".8